1. Field of the Invention
The present invention relates to a rotating machine for a vehicle or the like, which is equipped at its rotor with permanent magnets and field windings so that it is excited in a hybrid manner by the permanent magnets and the field windings, and to a vehicle which is equipped with the hybrid-excited rotating machine.
2. Background Art
The rotating machine having permanent magnets at its rotor is advantageous in that it is small but can generate a high torque, and is adopted in recent years for various applications. However, it fixes the quantity of magnetic flux that the rotor has the magnets. In case this rotating machine is employed as a generator, therefore, its output voltage is proportional to the revolving speed so that it widely changes in the application where the revolving speed range is wide as in a vehicular generator. Thus, it is difficult to apply the rotating machine to a vehicular generator, which is required to have its power generation controlled at a constant voltage such as 14 [V], for example.
As the vehicular generator of the prior art, therefore, there has been generally spread the so-called Rundell type synchronous machine, which is enabled to control the quantity of magnetic flux with the controling exciting current to the field winding of claw pole.
On the other hand, it has been conceived to acquire an idling stop function by connecting a semiconductor switching element with a vehicular generator and by using the generator as a starting motor. In case, however, the vehicular generator of the prior art is used as the starting motor, the starting torque is short for restarting the engine instantaneously. In order to enlarge that starting torque, it is conceivable to enlarge the size of the rotating machine. Because of the apprehension that claw-shaped pole is deformed by the centrifugel force, it is difficult to manufacture the rotating machine of a large size.
As another example of the prior art, therefore, it has been proposed to apply a hybrid-excited rotating machine, which has a revolving field for causing both the excitation by the field windings energized by a slip ring and a permanent magnet excitation, to a vehicular motor-generator. (Refer to JP-A-11-289732, for example).
The rotating machine of Patent JP-A-11-289732 is constituted, like the vehicular generator of the prior art having the general claw-shaped magnetic poles, to increase/decrease the magnetic flux linkage with the stator winding by energizing the field windings.